<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>固定导航条布局</title>

    <style type="text/css">
        .nav {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            background: red;
        }

        .xx {
            width: 800px;
            margin: 0 auto;
            background: yellow;
            text-align: center;
        }

    </style>
</head>
<body>
<div class="nav">
    <div class="xx">
        <span>234565</span>
        <span>234565</span>
        <span>234565</span>
        <span>234565</span>
    </div>
</div>
</body>
</html>